Welcome to Loch-tober!
By Dani Backman
Loch-tober is back. Each October, we highlight the science and stories behind lake management across the region. This year, we’re kicking off with Vancouver Lake: a 2,300-acre floodplain lake in Clark County facing toxic blooms and habitat stress. Herrera’s Phase II work included flushing channel evaluations and a pilot beach management plan to reduce algae and protect public health.
Let’s take a closer look at how science and collaboration are shaping the lake’s future.
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Loch-tober 2025: Turning the Tide on Vancouver Lake’s Water Quality
What does it take to restore a lake that’s been struggling for decades?
Vancouver Lake in Clark County, Washington, is one of the largest floodplain lakes in the state. It’s also one of the most challenged, facing toxic cyanobacteria blooms, poor water clarity, shallow depths, and invasive aquatic weeds that limit recreation and strain aquatic habitat.
Evaluating Long-Term Solutions
In 2024, Clark County partnered with Herrera to advance Phase II of the Vancouver Lake Management Plan. Our team led a comprehensive evaluation of flushing channel upgrades, using the most complete dataset ever assembled for the lake. Four conceptual designs were modeled for their ability to reduce algae blooms, improve ecological conditions, and meet permitting and cost constraints.
One option – constructing an open-channel bridge with backflow prevention – showed the greatest potential to reduce bloom days by over 75%, though it came with tradeoffs in cost and some fish passage benefits. Another option – using pumps to increase inflow – offered a lower-cost alternative with moderate improvements to water quality and lake depth.
Piloting Near-Term Actions
While lake flushing solutions are being considered, Herrera also developed and piloted the first Beach Management Plan at Vancouver Lake Regional Park. In summer 2024, we coordinated licensed applicators, monitoring teams, and public communication to test a peroxide-based algaecide treatment at the swim beach. The pilot confirmed the treatment’s effectiveness and highlighted the need for physical barriers to improve success – an insight that may inform future implementation.
Looking Ahead
These findings confirm that flushing enhancements are technically feasible, and beach management can be implemented successfully. The next step is to move from options to decisions: selecting a preferred flushing strategy, continuing beach monitoring and adaptive management, and forming a sustainable governance and funding structure to support long-term lake management.
Vancouver Lake is shifting from a pattern of recurring challenges to a sustained path of recovery: improving water quality, restoring habitat, and providing a healthier place for the community to enjoy.
Read more about the project on Clark County’s website.
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Contributing Author: Katie Sweeney
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